Field of the Invention
The present invention relates to a printing apparatus for printing on a printing medium and a determination method.
Description of the Related Art
Printing on a printing medium by an inkjet printing method is widely used because the apparatus arrangement is relatively inexpensive, and color stability is high. Printing media are provided for various purposes, including glossy/semiglossy paper, art paper, and coated paper for photo printing. On the printing apparatus side as well, parameters according to the characteristics of printing media are set to print images on the variety of printing media under optimum conditions. For example, an ink applying amount on a printing medium, a type of dye/pigment ink, and a conveyance amount and a conveyance speed in printing medium conveyance are set.
These parameters are set at the time of printing or before printing in accordance with the type of a printing medium. However, the type of a printing medium may be set by the user. For example, the user selects a printing medium from a list display via the user interface (UI) of a printer driver at the time of printing. Alternatively, when a printing medium is set on a printing apparatus, the user selects the type of the printing medium via a UI such as an operation panel formed on the printing apparatus.
On the other hand, since there are a variety of types of printing media, as described above, the user may make a selection error. If the user makes a selection error, the printing apparatus sets parameters for printing based on the user setting, and as a result, executes printing based on the wrong parameters.
In this case, if printing media have similar physical characteristics, the image only degrades. However, if printing media have different physical characteristics, ink overflow may take place to cause contamination in the printing apparatus, or ink transfer stain in the printing apparatus may be caused by wrong selection of dye/pigment ink. That is, the influence on the printing apparatus body may be fatal.
U.S. Pat. No. 6,425,650 describes comparing the reflection amounts of specular reflection and diffused reflection from a printing medium using a sensor including a specular reflection system and a diffused reflection system, and frequency-analyzing values continuously acquired by the sensor, thereby discriminating the type of the printing medium and selecting a print mode. In U.S. Pat. No. 6,425,650, the glossiness of the printing medium is detected from the ratio of specular reflection and diffused reflection, and the surface roughness of the printing medium is detected by frequency analysis, thereby discriminating the type of the printing medium.
The key factor of the physical characteristic that affects the main body, as described above, is the receptor layer of the surface of the printing medium. For example, whether to select dye ink or pigment ink is determined by the particle size relationship between ink and the receptor layer. For example, if the particles of the receptor layer are smaller than ink particles, as in so-called RC based glossy paper, the ink is fixed on the receptor layer. For this reason, if a wrong printing medium is selected, and printing is performed using an ink amount for it, the ink may be left on the surface of the printing medium and transferred to main body parts because of the ink amount that is not optimum. In coated paper or art paper, the particles of the receptor layer are generally formed large to preserve the texture of the paper. Hence, ink soaks into the base material of paper under the receptor layer and is fixed there. In such a printing medium, the amount of ink received by the receptor layer upon fixing is smaller than in the RC based glossy paper. For this reason, if printing is performed with a wrong ink amount, the ink may overflow on the printing medium, or the base material with the ink soaking may absorb water and deform, resulting in friction between the printhead and the printing medium.
As described above, the key factor to the feature of a printing medium is the structure of the receptor layer. The particle size of the receptor layer is several ten to several hundred μm. There are printing media of various thicknesses. Considering this, from the viewpoint of the cost and the sizes of optical system components, it is very difficult to optically construct a sensor capable of sufficiently ensuring a depth of field for a resolution of several ten to several hundred μm and build it in a printing apparatus.